Beneficiation of acidic minerals



Patented Sept. 25, 1951 BENEFICIATION OF ACIDIC MINERALS David W. Jayne, Old Greenwich, Harold M. Day,

Stamford, and Elmer W. Gieseke, Old Greenwich, Conn., assignols to American Cyanamid Company, New York, N. Y., a corporation of Main No Drawing.

4 Claims. 1 I r The present invention relates to the beneficia tion of mineral values of various ores by the use of a new class of reagents for selectively sepa rating acidic minerals from the other ore constituents. Still more particularly, the present invention relates to a novel process of froth flotation, using as promoters or collectors N -alkylated N-acylated polyalkylene polyamines, the acyl group being that of a fatty acid acylating agent. This application constitutes a continuation-inpart of our copending application, Serial No. 575,190, filed January 29, 1945, which is a continuation-in-part of its copending application, Serial No. 437,036, filed March 31, 1942 both now abandoned.

The present invention is primarily concerned with froth flotation. However, the teachings thereof are also applicable to the separation of acidic minerals by other processes dependent upon surface phenomena. Such processes include film flotation, agglomeration, tabling and other related operations. Similarly, the process is not necessarily limited to the treatment of any particular ore. However, its most important field of use is in the separation by froth flotation of silica and silicate minerals from such non-metallic ores as limestone, bauxite, barytes, ilmenite, calcite and the like. In particular, it is very successful in the separation of silicious gangue from phosphate ores. It also finds a considerable utility in the separation of silicious gangue from such oxidized iron ores as hematite, magnetite and the like.

In accordance with this invention, natural or partially processed ores, comprising a mixture of acidic minerals with other mineral constituents are subjected to a separation or concentration process in the presence of a promoter for the acidic ore minerals. The promoter used may be described as afattyacid acylated derivative of an N-alkylated polyamine. If so desired a mixture of such reagents may be employed.

The reagents of the present invention are effective promoters or collectors for negatively charged or acidic ore materials generally and said acidic material may either be worthless gangue or valuable ore constituents. The most important uses are, however, in connection with the froth flotation of silica from non-metallic ores in which the silicious gangue may represent a minor proportion of the ore rather than metallic and sulfide ores in which the gangue usually represents the major proportion of theores. Representative acidic ore materials are the feldspars, quartz, pyroxenes, the spinels, biotite, muscovite, clays and the like.

- method of preparation.

Application March 10, 1948, Serial No. 14,156

In the past, a number of reagents have been proposed for similar purposes. Most of them, however, have not been as satisfactory for all purposes as might be desired. Many of them are specific to certain minerals, others are not sufliciently available at all times, and still more, of them suffer an economic disadvantage due to relatively expensive materials used in their preparation.

Therefore, the principal objects of the present invention are to provide a class of reagents which is readily prepared; which is not necessarily specific to a particular type of ore; which is readily prepared from commonly available materials; which may be used successfully in economic competition and which exhibits a high degree of selectivity for acidic minerals in the presence of non-metallic minerals.

In general it has been found, in accordance with the present invention, that all of the principal objects are attained by the use of a group of reagents which include broadly the derivatives of N-alkylated polyamines obtained by a reaction with a fatty acid acylating agent.

In accordance with the present invention, we have found that while the polyalkylene polyamines themselves have no efiective promoting action for acidic ore minerals, they may be readily converted into effective promoters. This is accomplished by replacing one of the hydrogens on a terminal nitrogen with a short chain alkyl or hydroxy alkyl group and by replacing one of the hydrogens on a difierent terminal nitrogen with theacyl radical of an aliphatic fatty acid of about 8 to 32 carbon atoms. The order of making such plural substitutions is not critical. The resulting compounds are of the formula:

pared by several difierent methods and the in-' vention is not particularly concerned with their In general, we have found the following methods to be satisfactory. The alkylated polyalkylene polyamines are prepared by reacting a polyalkylenc polyaminc, such as for example, diethylene triamine, triethylene tetramine, tetraethyl pentamine, dipropylene triamine, or mixtures of such polyamines with an alkylating agent, such as lauryl bromide, ceiyl bromide, or similar alkylating agent having from 5 about 8 to not more than about 32 carbon atoms.

The mono, or di-alkyl derivatives are obtained depending upon the quantity of alkylating reagent employed. In the case of the dior polyalkylated derivatives we can use more than one 10 alkylating agent and obtain two or more different alkyl substituents. Suitable alkylating agents that may be used for producing polyalkyl derivatives of the higher alkylated polyamines include short chain aliphatic alkylating agents and other alkylating agents such as methyl bromide, ethyl iodide, ethylene chlorohydrin, esters of chloracetic acid, esters of chlorhydrins, benzyl chloride, and the like. The following example illustrates the preparation of an N-alkyl polyalkylene polyamine; namely, N-cetyl triethylene tetramine acetate.

EXAMPLE 1 A mixture of 23 grams of cetyl bromide and 25 56 grams of triethylene tetramine was heated for five hours at 150 C. in an oil bath, then cooled to room temperature when the reaction mix separated into two layers. The top layer was removed, added to 300 cc. of a 3% aqueous NaOH solution then salt added to the mix to salt out N-cetyl triethylene tetramine as an oil. The oil was extracted from the salt solution with benzol. The benzol solution was heated to 130 C. to remove the benzol. The product, N-cetyl triethylene tetramine, was a pale amber-colored oil. One molar equivalent of acetic acid was added to the product to form the acetate which was soluble in water.

Any one of the monoor di-alkylated compounds prepared by the foregoing method may be reacted with a fatty acid acylating agent to produce N-alkylated-N'-acylated polyalkylene polyamines. For instance, one mol of N-decyl diethylene triamine is heated to about 185 C. with the fatty acid equivalent of one mol of coconut oil. The same result may be achieved by first forming the fatty acid amide by reacting one mol of diethylene triamine by heating with the fatty acid equivalent of one mol of coconut oil to 180 C. to 190 C. and then alkylating this amide by treatment with decyl bromide.

The preparation of the reagents 9f the present invention is illustrated by the following examples. However, since the invention is not concerned with the method of manufacturing, these examples are illustrative only and not by way of limitation.

mlMPLEii The mono-coconut fatty acids amide of a mixture of polyethylene polyamines (containing diethylene triamine, 25% triethylene tetramine and 25% tetraethylene pentamine) was prepared by heating a mixture of grams of coconut 75 4 oil and 67.5 grams of the mixed polyethylene polyamines to C. A mixture of 70 grams of this product and 38 grams of 2-bromo-octane was heated to C. under a reflux condenser until refluxing stopped, then cooled to room temperature. The alkylated product was a soft paste, soluble in water.

The polyalkylene polyamines that may be em ployed for preparing our reagents may be represented by the following general formula:

in which n, m, and a: are small numbers.

The polyalkylene polyamines of the above formula may be produced by heating an alkylene chloride with ammonia under pressure at a temperature of about 80-120" C. When ethylene chloride is employed there is obtained a mixture of diethylene triamine, triethylene tetramine, tetraethylene pentamine, and ethylene diamine. The ethylene diamine can be removed from the mixture of the higher polyethylene polyamines by distillation. It is, of course, understood that when propylene chloride, butylene chloride, amylene chloride, and the like, are employed instead of ethylene chloride in reacting with ammonia, the corresponding polyalkylene polyamines are obtained. The expression polyalkylene polyamines employed in the claims, therefore refers to and includes any one of the polyalkylene polyamines referred to above or to a mixture of such polyalkylene polyamines. These polyamines derived from alkylene compounds are chain compounds having an amino group on each end of the chain, these terminal amino groups being separated by at least one -a1ky1ene NH-alkylenegrouping. Illustrative formulae for some of the polyalkylene polyamines employed are as follows:

Triethylene tetramine NH: CHz- CE-NH- CHz-CHz-NH- CHr-CHz-NH:

Dipropylene triamine:

NH2CHCH2NH-CH-CHz-NH2 H. ts.

Representative polyalkylene polyamines which may be employed in alkylating and condensing with fatty acids are diethylene triamine, dipropylene triamine, dibutylene triamine, triethylene, tetramine, tetraethylene pentamine, or mixtures of any two or more of such polyamines either as relatively pure compounds or crude mixtures. In general they are polyamines, the different amino groups of which are separated from one another by a hydrocarbon radical containing from 2 to 12 carbon atoms.

The compounds used in the present invention are usually homogeneous viscous pastes which 65 will combine with acids, such as formic, acetic,

hydrochloric, and the like, to yield salts which are soluble in water. They may be used in flotation processes in the form of these water-soluble salts or the free base may be used provided satisfactory dispersion is obtained.

Either the saturated, unsaturated, or hydroxy fatt acids may be employed for reacting with the polyamines to produce the N-alky1N'-acyl polyalkylene polyamines, the preferred ones being those having at least nine carbon atoms, for example, lauric, palmitic, stearic, oleic, ricinoleic, capric, myristic, mixturesof such acids and especially mixtures of the fatty acids obtained from the fats and oils of either vegetable or animal sources or their glycerides such as those in coconutoil, palm oil, palm kernel oil, cottonseed 011.

corn oil, linseed oil, olive oil, peanut oil, fish machine, being conditioned with the pulp for three seconds without air. Air was then admitted to the machine and the resulting froth concentrate collected until the froth became barren. The test products were then dried, weighed, and assayed. The reagents used and the metallurgical results are shown in the following table.

Table Concentrate Telling M ,51% {Regents Lbs./Ton Insol. Per Cent Per Cent g gh Per Cent Per Cent ,33 8% of Feed Wt. Insol. ML Wt. Iusol. ML

2 54,54 62.09 $3.28 98.22 37- {Pine 0 1 0 12 a: N-stearoyl-N'-liydroxyethyl diethylenetriamine hydrochloride. I

oils, and the like, as well as carboxylic acids such as talloel and naphthenic acid.

While, as stated heretofore, the present invention is not limited to the treatment .of any particular ore material, it has been found to be well suited for froth flotation of silica from .phosphate rock and is the preferred embodiment of the invention. In the processes of removing silica from phosphate rock, the conditions are such that practically complete removal of the silica must be accomplished in order to produce a salable phosphate material. It is therefore, an advantage of this invention that our reagents not only effect satisfactory removal of the silica but are also economical in amounts used. The quantities required range from 0.2 pound per ton of ore depending upon the particular ore and the particular reagent. The invention is not, however, limited to such quantities.

The reagents of the present invention may be used alone or in mixtures with other promoters.

- They may likewise be used in conjunction with other cooperating materials such as conditioning reagents, oily or fat materials, such as hydrocarbon ciis, fatty acids, or fatty acid esters.

When the reagents of the present invention are employed as promoters in the froth flotationof silica from phosphate rock, which is the preferred embodiment thereof, the condition may be varied in accordance with procedures known to those skilled in the art. The reagent may be employed in the form of aqueous solutions, emulsions, mixtures, or solutions in organic solvents, such as alcohol and the like. The reagent may beintroduced into the ore pulp prior to the actual concentration operation. They may also be stage fed into the flotation circuit.

The application of the present invention will be further illustrated in conjunction with the following illustrations of ore beneflciation. Again it should be pointed out that these examples are by way of illustration only. All parts are by weight unless otherwise noted.

EXAMPLE 4 A sample of Florida pebble phosphate was made into a fine flotation feed (-35+200 mesh) by scrubbing, polishing, and desliming until the feed was substantially slime free. This sample was divided into a number of portions, each of which successively was diluted to about 22% solids with water and treated in a Fagergren flotation machine. The particular reagent or reagent combination was added in the flotation b: N-lauroyl-Noctyl diethylene triamine hydrobromide.

The N-alkylated polyalkylene polyamines and their derivatives as used in the present invention are not used as frothers or frothing agents. In-

alcoholic frothers and the like which are com-.

mercially available. Consequently in the practice of this invention, the promoter will always be used in excess of the amount of material normally fed as a frother, i. e., in excess of about 0.10-0.12 lb./ton of ore treated.

We claim 1. In the beneficiation of ores containing acidic silicious minerals by floating a concentrate of the acidic silicious minerals therefrom, the improvement which comprises subjecting an aqueous pulp of the ore to agitation and aeration in the presence of at least about 0.2 lb. per ton of a collector and a relatively small amount of a nonselective frothing agent, said collector being selected from the group consisting of those compounds represented by the formula:

wherein n and x are small integers, R'CO- is' the residue of an 8 to 32 carbon atom fatty acid, and R is a substituent selected from the group consisting of short chain alkyl and hydroxy alkyl radicals.

2. A process according to claim 1 wherein the ore is a phosphate ore containing acidic silicious gangue.

3. In the beneflciation of low-grade phosphate ores by floating acidic silicious gangue therefrom, the improvement which comprises subjecting a pulp of the ore to froth flotation in the presence of at least about 0.2 lb. per ton of a collector and a relatively small amount 'of a non-selective frothing agent, said collector being a watersoluble addition salt of N-stearoyl-N'-hydroxyethyl diethylene triamine, whereby a major porfrothing agent, said collector being a. watersoluble addition salt of N-1auroy1-N'-octyl diethylene triamine, whereby a major portion of the acidic silicious gangue is concentrated in a supernatant froth layer above the pulp.

DAVID w. JAYNE. HAROLD M. DAY. ELMER w. GIESEKE.

REFERENCES CITED The fbllowing. references are of record in the file of this patent:

UNITED STATES PATENTS 2,236,530 Epstein Apr. 1, 1941 

1. IN THE BENEFICIATION OF THE ORES CONTAINING ACIDIC SILICIOUS MINERALS BY FLOATING A CONCENTRIC OF THE ACIDIC SILICIOUS MINERALS THEREFROM, THE IMPROVEMENT WHICH COMPRISES SUBJECTING AN AQUEOUS PULP OF THE ORE TO AGITATION AND AERATION IN THE PRESENCE OF AT LEAST ABOUT 0.2 LB. PER TON OF A COLLECTOR AND A RELATIVELY SMALL AMOUNT OF A NONSELECTIVE FROTHING AGENT, SAID COLLECTOR BEING SELECTED FROM THE GROUP CONSISTING OF THOSE COMPOUNDS REPRESENTED BY THE FORMULA: 